Abstract Detail

Phylogenomics

Zhou, Wenbin [1], Xiang, Jenny [2], Wen, Jun [3].

Phylogenomics of Nyssa from single copy genes and Fluidgim sequencing – insights into biogeography and character evolution.

Nyssa (Nyssaceae) represents a classic example of the well-known eastern Asian-eastern North American floristic disjunction. The genus has 3 species in eastern Asia, 4 species in eastern North America, and 1 species in central America. Species of the genus are ecologically important trees in eastern North American and eastern Asian forests. The distribution of living species and a rich fossil record of the genus make it an excellent model for understanding the origin and evolution of the well-known eastern Asian-eastern North American floristic disjunction. However, despites the small number of species, relationships within the genus has remained unclear and have not been elucidated using a molecular approach. Here we employed fluidgim sequencing to obtain DNA sequences from 38 single copy nuclear genes for phylogenetic analyses. Our results from maximum likelihood (ML) analysis of the concatenated data using raxml and from coalescent analysis of individual gene data using *BEAST2 (species tree) showed N. talamancana from central America diverged off first in the genus. The remainder of the genus diverged into three lineages rapidly: N. sinensis - sylvatica complex (N. sylvatica, and N. biflora), N. aquatica - N. ogeche, and N. javanica. The relationships among them differed between the ML tree and species tree. is conflicting between gene tree and species tree, but both were not strongly supported. Divergence time dating using BEAST estimated the stem age of Nyssa to be 78.8 myr (95% HDP: 73.2 myr - 95.4 myr) in the late Cretaceous. The divergence time of N. talamancana and the three aforementioned lineages was estimated to be 49.8 myr (95% HDP: 47.6 myr - 54.0 myr) in the Eocene. Reconstruction of ancestral distributions were performed using S-DIVA based on the phylogeny including 12 fossil species as well as using model based DEC method based on dated phylogeny of living species. Based on results from these analyses and evidence from divergence time and the Earth’s paleontological history, the biogeographic history of Nyssa was inferred to have an Eurasia origin, followed by subsequent dispersal into America and back to Asia and Europe again during the Paleogene and Neogene. This history likely involved the North Atlantic land bridge for the Paleogene dispersal to America and the Bering land bridge for the later Neogene dispersal to Asia and Europe. We also investigated the evolution of morphological and ecological characters within the genus to gain insights into evolutionary consequences of geographic isolation in the genus.

1 - North Carolina State University, Plant & Microbial Biology, Box 7612, 100 Derieux Place Gardner Hall 2115, Raleigh, NC, 27695, United States
2 - North Carolina State University, Gardner Hall 2115, Campus Box 7612, Gardner Hall 2115, Raleigh, NC, 27695, United States
3 - Botany, MRC-166 National Museum Of Natural History, 10th St. & Constitution Ave., NW, Mrc 166, Washington/DC, 20013, United States

Keywords:
eastern Asia-eastern North American disjunction
Nyssa
Fluidigm sequencing
Ancestral character estimation
Biogeography.

Presentation Type: Oral Paper
Session: 11, Phylogenomics II
Location: 114/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 4:00 PM
Number: 11008
Abstract ID:521
Candidate for Awards:None